Study On Preparation And Properties Of Waste Paper Fiber/Nanocellulose/PLA Composites

With the development of biodegradable composite materials,polylactic acid(PLA)has received widespread attention due to its good environmental performance.But at the same time,PLA has limitations in areas with high brittleness and high cost.Nanocellulose is a biological nanomaterial with high performance,which can improve the defects of PLA characteristics.While waste paper fiber is economical,environmentally friendly and easy to obtain,which has important practical significance for the application of PLA composites.This paper uses office waste printing paper/copy paper as raw materials to obtain nanocellulose by sulfuric acid hydrolysis method.The effects of different mass fraction NCC/PLA binary composites and WF/NCC/PLA ternary composites,as well as different kinds of modifier modified WF/NCC/PLA composites on mechanical properties,fiber structure,thermal stability,crystallization properties,water absorption properties,degradation properties and tensile section morphology were studied.The results show that:(1)The overall yield of nanocellulose obtained by alkali treatment is higher than that of non-alkali treatment.The best yield is 35.6%from 66%of alkali treatment.The size of nanocellulose particles is relatively small,with a larger aspect ratio.The basic characteristic peaks of nanocellulose before and after alkali treatment are the same,but the nanocrystalline cellulose has higher crystallinity and larger grain size after alkali treatment,and its thermal stability is better than that of nanocellulose without alkali treatment.(2)The overall mechanical properties of NCC/PLA composites have been improved.The 3%NCC/PLA composites have the best comprehensive mechanical properties and are more uniformly dispersed.The crystallinity of NCC/PLA composites increased,the water absorption performance increased with the nanocellulose mass fraction,and the degradation performance trend was the same as the water absorption performance.The phenomenon of material corrosion degradation occurred.(3)The basic characteristic peaks of waste paper fibers and nanocellulose are the same.The overall mechanical properties of the composites decreased after adding waste paper fiber,but the mechanical properties of the composites were improved compared with those of PLA.15%WF/NCC/PLA composite material has the best comprehensive mechanical properties.The thermal stability of WF/NCC/PLA composites decreased.The crystallinity increased to 22.4%,and the interface compatibility of the composites was poor,with a clear boundary with the matrix.The water absorption and degradation rate of WF/NCC/PLA composites increased.Acid degradation has caused damage to the basic structural form of the composites.(4)The bending performance of the modified WF/NCC/PLA composites has been improved as a whole.The thermal stability of the composites after titanate,alkali treatment,PEG and composite modification have been reduced correspondingly.The crystallinity have been improved,and the water absorption and degradation properties have decreased.Moreover,the interface between the modified composite fiber and the matrix is obviously improved.The interface bonding force of the composites is improved,and the comprehensive mechanical properties of the modified composites are increased.